1. Field of the Invention
The present invention relates to a method for controlling communications in a wireless data communication network such as Bluetooth.
2. Description of the Related Art
Conventionally, information processors such as personal computers are commonly used in the form in which a plurality of information processors are connected mutually so as to form a network. Considerable attention is paid to Bluetooth as a technology that can form a network for wireless communications between various electronic apparatuses such as portable telephones, various personal computers including portable computers, digital cameras, and portable video games. A general commentary article about Bluetooth is No. 759 (Dec.r, 13, 1999) of Nikkei Electronics published by Nikkei BP Co. LTD., for example.
Japanese Unexamined Patent Publication JP-A 2000-224156 (2000) discloses a technique for enhancing security with encryption in a close range wireless communication network such as Bluetooth. Japanese Unexamined Patent Publication JP-A 2001-8274 (2001) discloses a technique allowing hand-free talk in which an audio apparatus in a car and a mobile phone are connected by a short range wireless connection such as Bluetooth so that a driver of a car can use a mobile phone via the audio apparatus safely without holding the mobile phone set by hand. Japanese Unexamined Patent Publication JP-A 2000-261560 (2000) discloses a technique about a wireless acoustic coupler modem that connects wirelessly an acoustic coupler and a computer by wireless communications such as Bluetooth or by infrared communications such as IrDA (Infra-red Data Association). Japanese Unexamined Patent Publication JP-A 2000-276269 (2000) discloses a technique that connects between a plurality of computers and a data input apparatus such as a keyboard or a mouse by a wireless connection such as Bluetooth and performs switching.
In a network formed with computers or the like, in general, high-speed and high reliability are promoted. For example, Japanese Unexamined Patent Publication JP-A 2000-32005 (2000) discloses a technique that divides data to be transmitted into a plurality of segments, and transfers each segment in a plurality of asynchronous communication packets under the rule that if the transfer of segments is interrupted, retransmission starts with a packet whose transfer is interrupted.
Priorities are set for a selection among a plurality of apparatuses connected to a network so as to prevent a plurality of apparatuses from operating at the same time. Japanese Unexamined Patent Publication JP-A 11-288362 (1999) discloses a technique in which a printing apparatus that outputs in the previous time of a plurality of printing apparatuses connected to a network is used by priority. Japanese Unexamined Patent Publication JP-A 2000-132494 (2000) discloses a technique that allows only a newly connected audio apparatus of a plurality of audio apparatuses connected via USB (Universal Serial Bus) to output.
Although a wireless data communication network such as Bluetooth connects various apparatuses flexibly, it utilizes a 2.4 GHz frequency band called ISM (Industry Science Medical) band and uses a frequency hopping spreading modulation system so that a difference in the way to change the frequency prevents other communications from being mixed. Furthermore, carrier sensing, which is commonly performed in other network connection methods, is not performed, and when a problem is caused in transfer of data, for example, because of collision of carriers, the problem is addressed by retransmission of the data.
Therefore, when forming a network using Bluetooth, connection forms as to where to receive which data and reconnection conditions for the time when connection is cut during data transfer have to be set. However, techniques that make it easy for users who have little technical knowledge to actually perform these connections have not been developed yet.